Experiments on a 3D Rectangular Blade Undergoing Plunging Motion

3D rectangular blade with a semi-span aspect ratio 2.4 is measured in a wind tunnel at a Reynolds number of 0.27 × 10 ⁶ to investigate the three-dimensional effects of plunge motion on lift coefficient variations. The measured surface pressure integration method is used to calculate the sectional lift coefficients at the blade’s root, mid, and tip sections. For this study, a novel apparatus was designed, manufactured, and calibrated to simulate the almost general motion of a wing. To analyze the effects of motion parameters on lift evolutions, experiments were carried out with various plunge amplitude ratios (\(\:\stackrel{-}{h}/c\)) and reduced frequencies ( k ), using the mentioned mechanism. As a result of tip-vortex and cross-flow, the lift history of tip sections shows a different behavior. Lift hysteresis is also affected by the model's structural properties. Due to tip vortices and cross flow perturbations, lift hysteresis loops differ from the conventional elliptic shape of 2D airfoils.